Method for making a bobbin assembly



Oct. 7, 1969 CQNE 7 3,471,607

METHOD FOR MAKING A BOBBIN ASSEMBLY Filed Jan. 11, 1968 2 Sheets-Sheet l NVENTOR LLOYD E. CONE ATTOR NEYS Oct. 7, 1969 1.. E. CONE METHOD FOR MAKING A BOBBIN ASSEMBLY 2 Sheets-Sheet 2 Filed Jan. 11, 1968 INVENTOR LLOYD E. CONE WWWMW ATTORNEYS Unitcd States Patent US. Cl. 264-449 Claims ABSTRACT OF THE DISCLOSURE The method of this invention comprises the steps of providing a one piece plastic tube having a cop of thread wound thereon, and then swaging the inside surfaces of each end portion of the tube radially outwardly to invert the end portions of the tube to form end flanges engaging opposite axial ends of the cop.

This is a continuation-in-part of applicants prior copending application Ser. No. 522,646, filed Jan. 24, 1966 now abandoned.

This invention relates to sewing machine bobbins and particularly concerns improvements in the manufacture of so-called rotary bobbins ready-wound for use in high speed sewing machines.

A primary object of the invention is to provide improved methods of manufacture particularly suited for rapidly producing low-priced bobbins of the type described above that may be simply thrown away when the thread is completely paid-oh? the bobbin.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

In the drawings:

FIG. 1 is an isometric view showing an unfinished bobbin unit;

FIG. 2 is an isometric view, partly broken away showing a machine for use in making bobbins in accordance with this invention;

FIG. 3 is an enlarged section view, partly broken away, taken generally along line 3-3 of FIG. 2 showing a pair of die members in a withdrawn position;

FIG. 4 is a section view, partly broken away, similar to FIG. 3 showing the die members in an extended position;

FIG. 5 is an enlarged section view, partly broken away, showing the die members in an extended position forming a bobbin unit positioned therebetween;

FIG. 6 is an isometric view showing a finished bobbin; and I FIG. 7 is an isometric view, partly broken away, showing a pair of cop compression members in retracted position.

Referring now to the drawings in detail, an unfinished bobbin unit 10 is shown in FIG. 1 having a cylindrical mass or cop 12 of thread wound on a plastic tube 14. The tube 14 is formed of a predetermined length of suit- 3,471,607 Patented Oct. 7, 1969 able cold workable plastic tubing or thermoplastic tubing such as polystyrene. The cop 12 has an axial length of about one-half that of the tube 14 and is centered between its opposite ends.

To form the unfinished bobbin unit 10 into a finished ready-wound one-piece bobbin 16 of the type shown in FIG. 6 in accordance with the method of this invention, a machine 18 is provided having a base 20 supporting a frame or housing 22 upon which is mounted an elongated upright magazine 24 for holding a stack of bobbin units 10. A number of bobbin units are fed into a mouth 26 at the top of the magazine 24 to gravitate through a longitudinally extending passage 28 to a bottom discharge opening 30 leading into an upper portion of the housing 22. The passage 28 in the magazine 24 is configured to retain the tubes 14 of the stacked bobbin units 10 in a horizontal position. Electrical heating elements 32, 34 connected to a suitable power source, not shown, are provided in the magazine 24 adjacent the opposite ends of the stacked bobbin units 10 to preheat the end portions of their tubes 14.

After being preheated in the magazine 24, the unfinished bobbin units 10 are successively fed through the discharge opening 30 onto a positioning block 36 spring mounted for vertical movement in the housing 22. The positioning block 36 is loacted between a pair of coaxial flange-forming die members 38, 40 respectively provided with heating elements 42, 44 similar to those in the magazine 24. The die members 38, 40 are rigidly fixed to a pair of cam operated members 46, 48 for horizontally reciprocating the die members along a common axis of movement. The lower ends of the cam operated members 46, 48 have integrally formed contoured followers 50, 52 respecively engaging opposed camming surfaces 54, 56 of a rotary cam 58 fixed to a shaft 60 rotatably supported by the housing 22.

In order to successively feed the bobbin units 10 in a synchronized operation with the reciprocation of the die members 38, 40, two pairs of pins 62, 64 are shown for illustrative purposes as being mounted in the magazine 24 just above the discharge opening 30 to alternately reciprocate between extended and retracted positions relative to the passage 28. The pins 62, 64 are actuated, e.g., by a conventional penumatic cylinder, not shown, operatively connected to a hand-operated lever 66 secured to an extending portion of the shaft 60 so as to release the lowermost bobbin unit onto the positioning block 36 when the die members 38, 40 are withdrawn into the position shown in FIG. 3. To assist in positioning each bobbin unit 10 in axial alignment with the die members, the latter have integrally formed central projections 68, 70 extending coaxially outwardly in oppositely facing relation for insertion into opposite end portions of the tube 14.

By raising the lever 66 from its full line position shown in FIG. 2 to its illustrated broken line position, die members 38, 40 are simultaneously moved inwardly toward one another whereby their projections 68, 70 enter opposite end portions of the tube 14, and the positioning block 36 is cammed downwardly out of the way by the die members 38, 40 riding over beveled shoulders 72, 74 formed on the positioning block. The inside surfaces of the tube 14 thus are engaged by the heated die members 38, 40 whereby the opposite end portions of the tube are forced radially outwardly under heat and pressure provided by the die members. The die members move inwardly toward one another to an extent limited by the projections 68, 70 which abut in the extended position shown in FIG. 4 wherein the end portions of the tube 14 are in pressing engagement with the axial ends of the cop 12. This ensures that the thread will be properly held without binding in the finished bobbin.

When the hand-operated lever 66 is lowered, the die members 38, 40 are disengaged from the bobbin and retracted under the biasing force of a coil compression spring 76 seated between the cam operated member 46, 48, and the finished bobbin is then free to drop through a correspondingly dimensioned vertical slot 78 in the positioning block 36, onto a ramp 80 formed in the base leading from the housing 22.

By first preheating each tube 14 as described above, its opposite end portions are initially softened and are partially inverted outwardly to expedite the flange forming operation whereby the inside surfaces of the end portions are conditioned to be smoothly and rapidly pressure radially outwardly by the die members 38, 40 in accordance with the invention. Thus, a finished ready-wound rotary bobbin 16 is provided as shown in FIG. 6 having parallel radial flange portions 82, 84 integral with opposite ends of a tubular core portion 86 for engaging and supporting the axial ends of the cop 12. To ensure that the flange portions 82, 84 will be uniformly pressed into engagement with the axial ends of the cop 12, the die members 38, 40 are contoured such that the inner and outer peripheral edges 87, 88 of each outside face of the flange portions 82, 84 are contained in a common plane. The resulting unitary structure of the bobbin is particularly suited to retain cops of relatively incompressible thread, such as nylon.

Referring now to FIG. 7, machine 18 is shown provided with two pairs of flat half moon type compression members or plates 90, 92 usable in effecting precision manufacture of bobbins according to this invention. The pairs of compression plates 90, 92 are respectively carried on operators 94, 96 mounted in any suitable manner for reciprocating movement along a common axis perpendicular to the axis of movement of the die members 38, 40 and midway between the same. Operators 94, 96 move toward and away from one another between relatively extended and retracted positions and are preferably simultaneously driven, independently of the die members 38, 40. The compression plates 90, 92 are illustrated as being supported on pins such as at 98 and spring biased laterally outwardly of their respective operator 94, 96 so as to be readily positioned adjacent an axial end of a cop 12 of a bobbin unit which is to be formed in accordance with this invention.

With the bobbin unit supported by the die members 38, 40 in relatively retracted position, the operators 94, 96 are fully extended to position the compression plates 90, 92 adjacent opposite axial ends of the cop 12 in overlying relation thereto. The die members 38, 40 then are moved inwardly toward one another to press or swage opposite end portions of the tube 14 over exposed faces of the compression plates 90, 92 which are then moved inwardly to uniformly compress the cop 12 axially, responsive to movement of the die members 38, 40 into their fully extended position. The operators 94, 96 and the die members 38, 40 are then retracted to release the bobbin whereupon its cop 12 springs back into engagement against the inside faces of the flanged end portions of the bobbin assembly which is then completely formed.

By virtue of positioning the flat compression plates 90, 92 adjacent the opposite axial ends of the cop 12 before swaging over the end portions of the tube 14, the inside face on each flange portion 82, 84 is assured of being flat thereby providing uniform engagement with opposite axial end of the cop 12 and virtually eliminating any possibility of the thread becoming snarled or bound up during use.

In view of the above disclosed methods of manufacture, the is minimal waste of material and no need whatsoever for transferring the bobbin unit from one machine to another in the course of forming flanges to engage the bobbin cop. There is also no need for individually wrapping each finished bobbin in cellophane, e.g., to prevent undesirable swelling of the end flanges or to prevent their popping off the core as normally encountered with conventional paper disk bobbins. Moreover, a precision cross wound cop is readily incorporated in the finished bobbin to provide maximum thread yardage rather than being limited to a parallel winding or conventional spool type winding commonly associated with bobbins of a premolded type.

It will be seen that the above described methods for making the bobbin of this invention are of notable use in rapidly producing low priced disposable bobbins which may be simply replaced when the thread is completely paid-off the bobbin. The unitary structure of the bobbin assures that the thread will be properly held without binding or becoming snarled. Moreover, the disclosed bobbin automatically provides continuous control during withdrawal of thread in a lightweight resilient body which is adapted to retain its shape under varying atmospheric conditions.

I claim:

1. A method of making a ready-wound one piece bobbin comprising the steps of providing a cylindrical wound mass of thread constituting a cop on a plastic tube with opposite axial ends of the cop each defining an annulus spaced inwardly from opposite ends of the tube, heating opposite end portions of the tube for partially inverting the same, positioning a flat compression member adjacent each axial end of the cop, pressing the inside surface of each end portion of the tube radially outwardly throughout the width of the annulus at each end of the cop and to further invert the end portions of the tube into flanged end portions integral with a tubular core portion, moving each compression member toward the other during the pressing step to ensure uniform axial compression of the cop and a flat inside face on each pressed flanged end portion of the bobbin, and retracting the compression members from the bobbin thereby to provide a unitary bobbin having flanged end portions in direct contact with the cop of thread.

2. A method of making a ready-wound one piece bobbin comprising the steps of providing a cop of thread with opposite ends each having an annulus of a predetermined width, providing a plastic tube of a predetermined length sufficient to be inserted into the cop and to extend beyond each end of the cop a distance approximately equal to the width of the adjacent annulus thereof, positioning the cop on the plastic tube with opposite axial end portions thereof each extending beyond the cop a distance approximately equal to the width of the adjacent annulus, compressing the axial end portions of the tube and guiding the same laterally outwardly throughout the full width of the adjacent annulus of the cop to deform the end portions of the tube into flanged end portions integral with a tubular core portion while applying uniform axial compression on the cop, and forming inner and outer peripheral edges on an outside face of each flanged end portion with said inner and outer peripheral edges thereof contained in a common plane.

3. The method of claim 2 further comprising the step of maintaining the cop in axial compression during the pressing step.

4. The method of claim 2 further comprising the step of heating opposite end portions of the tube for partially inverting the same before the pressing step.

5. A method of making a ready-wound one piece bobbin comprising the steps of providing a generally cylindrical wound mass of thread constituting a cop on a the other during the pressing step to ensure uniform 10 axial compression of the cop and pressing end portions of the tube into pressing engagement with the compression members to ensure a flat inside face on each pressed flanged end portion of the bobbin, and then retracting the compression members from the bobbin for elfecting direct engagement of the flanged end portions respectively with opposite axial ends of the cop to provide a unitary bobbin for holding the cop of thread.

References Cited UNITED STATES PATENTS 2,876,496 3/1959 Murphy 264-322 X 2,918,886 12/1959 Camp 242-469 2,985,405 5/ 1961 Eckhardt 242-169 3,013,310 12/1961 Foster et a1. 264323 ROBERT F. WHITE, Primary Examiner K. J. HOVET, Assistant Examiner US. Cl. X.R. 

